Quick connect hydraulic couplings typically include a male portion in operable engagement with a female portion. The male and female portions may be interconnected to a hydraulic hose, tubing, piping, machinery or open apparatus that utilizes internal pressure. Since many of these hydraulic hoses and interconnecting machinery utilize high pressure fluids, safety and operational considerations are paramount since an inadvertent disconnection of the coupling may result in serious injury or system failure. Such quick connect couplings are particularly desirable when the hose must be connected in a location that is not readily accessible since it eliminates the need for engaging a threaded connection and the associated danger of cross threading. Further, quick connect couplings generally eliminate the need for specific tools that might not fit in an available space proximate to the connection.
Historically, criteria that have driven the design of quick connect couplings have included the complexity and reliability of the male portion and female portion, and inherent manufacturing concerns which affect the complexity and location of the sealing elements such as o-rings or other seals. The location of safety locking components such as clips, ferrules and clamps have also greatly affected the cost and reliability of quick connect couplings, which further impact their economic viability.
It has also been critical that quick connect couplings are designed for safe and reliable use. Obviously, one of the primary objections is to provide a durable, leak-free connection. However, over time increasing emphasis has been placed upon safety. The quick connect characteristic of such couplings necessarily give rise to a greater risk of inadvertent and sudden disconnects, which may translate to catastrophic failure of the system or injury. This is particularly evident in environments where use of such couplings is generally appealing. These include industrial or heavy machinery operations where installations of fluid connections are numerous, dense, and almost inaccessible. Unexpected impacts or continuous vibrational loads upon quick connect couplings during normal operations or maintenance may increase the likelihood of inadvertent disconnects. Further, inadvertent disconnects on pressurized systems can lead to damaged or broken machinery, destroyed premises, loss of mission, severe injuries and even death.
In general, the male portion of a quick connect coupling typically includes a hose insert portion and a ferrule that is attached to an open end of the hose. The ferrule is then compressed about the hose that is positioned around the hose insert causing it to be permanently affixed. Merely pressing a stem of the male portion into the female portion, or similarly configured port, subsequently completes a flow path for a liquid or gas such as compressed air. Generally, the female portion, or port adapter, is threaded into place in a pre-assembly operation, or alternatively, is machined directly into then associated fixture, machine, or equipment. Thus, it is easy to ensure that the port is properly sized to receive the male portion.
Quick connect couplings have numerous uses and applications, including aerospace, automotive, construction, farming, etc. Generally, where there is a need for continuous connection and subsequent disconnection of fluid or gas lines, or the location of the intended connection makes it difficult or impossible to access, such that a threaded interconnection would be infeasible, a quick connect is ideal.
In operation, the male portion is typically provided with a groove for the receipt of a locking device. Generally, the locking device is a wedging ring that comprises a cylindrical member with an inner and outer diameter. The wedging ring includes a gap such that it is capable of resilient deflection to form a ring of smaller diameter. In some embodiments of the prior art such as the QC series sold be Swagelok®, the wedging ring is placed over a groove integrated into the outer diameter of the male portion. After insertion of the male portion into the female portion, a ring deflecting mechanism or sleeve is forced over the wedging ring, thereby deforming it into a groove located in the male portion to prevent disconnection. The sleeve is held in place over the wedging ring by a spring. To disconnect the two components, the sleeve is pulled towards the spring, thus releasing the wedging ring from the groove and allowing the two portions to be disengaged.
One drawback with prior art quick connect couplings is that the biasing means or spring that maintains the sleeve in the proper location may become worn over time such that the spring force acting upon the sleeve may be reduced allowing the sleeve to be more easily inadvertently displaced, thereby allowing the wedging ring to return to its nominal state and allow the coupling to disengage. Some prior art couplings have addressed this problem by adding a secondary locking device that resides between the sleeve and a protrusion, or bearing surface, situated on the male portion to prevent the sleeve from moving without initially removing the secondary locking device. However, these secondary locking devices are often bulky, occupy excessive space, and require additional steps for disconnection of the male portion and female portion of the coupling. In addition, outside influences such as component vibration may cause secondary locking devices to become dislodged from the quick connect, thereby allowing the locking mechanism to move and become disconnected. Further, prior art couplings generally do not prevent an intentional but inappropriate disconnection.
Another example of a quick connect coupling may be found in U.S. Pat. No. 6,637,781 to Seymour, which is incorporated by reference in its entirety herein. Seymour teaches a quick connect system that utilizes a male portion and a female portion that selectively interconnect. The male portion is adapted to receive a sealing device, such as an o-ring, and a resiliently deflectable wedging ring. Upon insertion of the male portion into the female portion, the wedging ring will selectively deflect and engage grooves in both portions to lock the system together. A spacer is positioned between bearing surfaces on each of the portions to prevent further insertion of the male portion into the female portion. To disconnect the coupling, a user removes the spacer from the coupling, thus allowing the male portion to be inserted further into the female portion, thus repositioning the wedging ring on the stem of the male portion. Once the wedging ring reaches a certain point on the stem, it deflects back to its nominal shape, thus allowing the male portion to be removed from the female portion. The wedging ring must then be removed from the female portion before the coupling may be used again. Thus, the interconnection and disconnection of the prior art coupling is complicated. The quick connect coupling disclosed in Seymour requires an additional component, or stop member, to ensure the coupling does not inadvertently disconnect. The complexity and additional components generally increase the cost to manufacture the coupling, and limits the application of the quick connect coupling to apparatus which do not have space limitations. Once again, this design does not prevent intentional and inappropriate disconnection when the hydraulic system is pressurized.
Thus, there is a long felt need for a quick connect coupling which may be disconnected under pressure, but which may be selectively interconnected and disconnected without the use of accessory tools or other cumbersome devices when pressure is released.